It is known to influence the boundary layer flowing along the surface of structural aircraft components such as the body, the wings, the tail assembly and along engine nacelles. For this purpose it is known to use suction generators having their own power source. Such separate power sources require their own fuel, they add to the weight of the aircraft, and they increase the maintenance effort and expense. Further, such suction generators in the form of compressors generally comprise rotating components which adversely affect the overall system reliability. Due to their own weight these compressors add to the fuel consumption of the aircraft in addition to requiring their own fuel.
It is known from German Patent Publication DE-AS 1,280,057 (Handley Page), published on Oct. 10, 1968 to equip aircraft wings with suction openings or porous elements in the outer wing skin requiring a substantial duct system connected to a suction generator arranged in the duct system or inside the aircraft. Details of the suction source are not disclosed. German Patent Publication DE 4,128,078 A1 (Coffinberry), published on Mar. 5, 1992 discloses a boundary layer suction system for an aircraft in which an ejector pump is used for the suction whereby the ejector pump itself is driven by an airflow generated by a suction air compressor unit driven by an electrical generator which in turn is driven by the gas turbine power plant of the aircraft. The sucked off boundary layer air is used as a source for compressed air and as cooling air for the environment control system (ECS). This type of generation of the suction air increases the operating costs of the aircraft so equipped, particularly since it increases the fuel consumption of the aircraft engines.
It is also known from German Patent Publication 736,114 (Wagner), published on Apr. 29, 1943 to connect an ejector pump for sucking off boundary layer air to the suction side of a precompressor of the internal combustion engine of the aircraft.
U.S. Pat. 3,149,804 (Litz, Jr.), issued on Sep. 22, 1964 discloses an anti-stall system in which a propellant gas generator is connected to an ejector for sucking off boundary layer air through holes in the wings.
German Patent Publication DE 3,621,783 (Pulch, Sr.), published on Jan. 7, 1988 discloses a hollow aircraft propeller wherein reduced pressure is generated to suck off boundary layer air from the surface of the propeller. The suction is derived from an ejector system driven by the engine exhaust gas.